The present invention relates in general to microwave signal processing circuitry and, more particularly, to a microwave filter illustrated in a bandpass filter implemented in microstrip circuitry for which it is initially being used.
Bandpass filters are designed to pass a desired range of frequencies and to reject others above and below the desired range of frequencies. A common characteristic of bandpass filters is that they also pass higher frequencies, usually at the third and higher odd multiples of the desired range of frequencies. When the passage of the higher frequencies is not desirable, additional filtering, such as a low-pass filter or a band-reject filter, is required to suppress the higher frequency responses of the bandpass filter. Such additional filtering requires the use of additional printed circuit board space, and the longer lengths traversed by the radio frequency signal causes additional losses.